Fuel used in an engine such as a diesel or petrol (gasoline) powered internal combustion (IC) engine may contain contaminants such as water or any other non-fuel fluid. Water present in the fuel tends to damage the fuel injection system and in extreme circumstances may lead to subsequent engine failure. Further, the engine efficiency may be reduced if the engine system works improperly due to such contamination. To solve the abovementioned problem, a fuel filter is used to separate fuel impurities and water particles prior to combustion.
Conventional fuel filters contain single or multiple filter media in order capture particulate matter. In addition water, by virtue of its higher density than petrol or diesel, tends to accumulate in the bottom of the filter housing.
The accumulated water should be drained off as soon it reaches to maximum level. If accumulated water surpasses the maximum level, it flows with the fuel inlet flow to the high pressure fuel system and affects the operation of the engine as described above, and may also damage the filter media.
In a conventional IC engine (such as those found in vehicles such as construction or agricultural machines, as well as in engines of electrical generators) manual drain off system is provided at the lower part of fuel filter to drain the accumulated water. In such a system the operator has to consistently monitor the water level and manually drain off water. In many instances, operators are not suitably trained, or simply forget to drain off water leading to the problems set out above.
It is known to provide an indication system remotely from the filter such as on a dashboard located in the operator cab. The indication system indicates the operator when water level reaches to the said maximum limit and further instructs the operator to drain off water.
KR20010019911 proposes a fuel filter provided with auto drain apparatus having an internal guided magnet mounted float located in the closed chamber. However, the abovementioned solution has some drawbacks. First, the magnet is mounted on the float hence it is exposed to the fuel contaminants which may result in damage to the magnet. Second, the weight is adjusted by a screw placed on the float, which may increase the possibility of permanent water penetration into the float. Third, the arrangement may be prone to clogging by the impurities. Finally, the float is solid and free to move in the closed chamber hence the operator may misled due to free movement of the float during tilting or inclination of the vehicle in which the engine is fitted as the float may falsely trigger the magnet detection sensor.
Another proposal is mentioned in patent publication no. U.S. Pat. No. 6,783,665. In this disclosure, there is a small clearance between the float and guiding means hence the float is prone to sticking in the chamber due to the build-up of fuel impurities. Second, although the system is automatic the operator intervention is still required for draining off water.
The present invention seeks to overcome, or at least mitigate some of the problems discussed above.